From 40b7318319281b1bdec804f6435f26cadd329c13 Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Tue, 21 Oct 2014 13:33:59 +0200 Subject: [PATCH] gpio: Support for unified device properties interface Some drivers need to deal with only firmware representation of its GPIOs. An example would be a GPIO button array driver where each button is described as a separate firmware node in device tree. Typically these child nodes do not have physical representation in the Linux device model. In order to help device drivers to handle such firmware child nodes we add dev[m]_get_named_gpiod_from_child() that takes a child firmware node pointer as its second argument (the first one is the parent device itself), finds the GPIO using whatever is the underlying firmware method, and requests the GPIO properly. Signed-off-by: Mika Westerberg Acked-by: Alexandre Courbot Acked-by: Grant Likely Signed-off-by: Rafael J. Wysocki --- drivers/gpio/devres.c | 32 ++++++++++++++++++++ drivers/gpio/gpiolib.c | 55 +++++++++++++++++++++++++++++++++++ include/linux/gpio/consumer.h | 7 +++++ 3 files changed, 94 insertions(+) diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c index 954b9f6b0ef8..13dbd3dfc33a 100644 --- a/drivers/gpio/devres.c +++ b/drivers/gpio/devres.c @@ -108,6 +108,38 @@ struct gpio_desc *__must_check __devm_gpiod_get_index(struct device *dev, } EXPORT_SYMBOL(__devm_gpiod_get_index); +/** + * devm_get_gpiod_from_child - get a GPIO descriptor from a device's child node + * @dev: GPIO consumer + * @child: firmware node (child of @dev) + * + * GPIO descriptors returned from this function are automatically disposed on + * driver detach. + */ +struct gpio_desc *devm_get_gpiod_from_child(struct device *dev, + struct fwnode_handle *child) +{ + struct gpio_desc **dr; + struct gpio_desc *desc; + + dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *), + GFP_KERNEL); + if (!dr) + return ERR_PTR(-ENOMEM); + + desc = fwnode_get_named_gpiod(child, "gpios"); + if (IS_ERR(desc)) { + devres_free(dr); + return desc; + } + + *dr = desc; + devres_add(dev, dr); + + return desc; +} +EXPORT_SYMBOL(devm_get_gpiod_from_child); + /** * devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional() * @dev: GPIO consumer diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 2bca0495cb46..58659dbe702a 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1734,6 +1734,61 @@ struct gpio_desc *__must_check __gpiod_get_index(struct device *dev, } EXPORT_SYMBOL_GPL(__gpiod_get_index); +/** + * fwnode_get_named_gpiod - obtain a GPIO from firmware node + * @fwnode: handle of the firmware node + * @propname: name of the firmware property representing the GPIO + * + * This function can be used for drivers that get their configuration + * from firmware. + * + * Function properly finds the corresponding GPIO using whatever is the + * underlying firmware interface and then makes sure that the GPIO + * descriptor is requested before it is returned to the caller. + * + * In case of error an ERR_PTR() is returned. + */ +struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode, + const char *propname) +{ + struct gpio_desc *desc = ERR_PTR(-ENODEV); + bool active_low = false; + int ret; + + if (!fwnode) + return ERR_PTR(-EINVAL); + + if (is_of_node(fwnode)) { + enum of_gpio_flags flags; + + desc = of_get_named_gpiod_flags(of_node(fwnode), propname, 0, + &flags); + if (!IS_ERR(desc)) + active_low = flags & OF_GPIO_ACTIVE_LOW; + } else if (is_acpi_node(fwnode)) { + struct acpi_gpio_info info; + + desc = acpi_get_gpiod_by_index(acpi_node(fwnode), propname, 0, + &info); + if (!IS_ERR(desc)) + active_low = info.active_low; + } + + if (IS_ERR(desc)) + return desc; + + ret = gpiod_request(desc, NULL); + if (ret) + return ERR_PTR(ret); + + /* Only value flag can be set from both DT and ACPI is active_low */ + if (active_low) + set_bit(FLAG_ACTIVE_LOW, &desc->flags); + + return desc; +} +EXPORT_SYMBOL_GPL(fwnode_get_named_gpiod); + /** * gpiod_get_index_optional - obtain an optional GPIO from a multi-index GPIO * function diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 12f146fa6604..00b1b70d68ba 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -94,6 +94,13 @@ int gpiod_to_irq(const struct gpio_desc *desc); struct gpio_desc *gpio_to_desc(unsigned gpio); int desc_to_gpio(const struct gpio_desc *desc); +/* Child properties interface */ +struct fwnode_handle; + +struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode, + const char *propname); +struct gpio_desc *devm_get_gpiod_from_child(struct device *dev, + struct fwnode_handle *child); #else /* CONFIG_GPIOLIB */ static inline struct gpio_desc *__must_check __gpiod_get(struct device *dev, -- 2.20.1